Pulsation-preventing mechanism for centrifugal compressors.



R. H. RICE. PULSATION PREVENTING MECHANISM FOR CENTHIFUGAL COMPRESSORS.

Patented Oct. 8, 191a,

APFLICATION FILED FEB. 2.1'917- 1.,2so,s43. I

Figl.

Inventor:

Richard H.Rice, b5

albumin 11. man,

F LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL, COMPANY, A CORPORATION OF NEW YORK.

eme

' rvisa'non-rnnvnnrmc MECH NISM FOR, CENTRIFUGAL comrnnssons;

:-*Be it known that I, RICHARD Bron, a gc'iti'zen of the United States, residing at 6 Lynn; in the county of Essex, State of Mas- 6 sachusettsyhaveinvented certain new and usefullmprovements in Pulsation-Preventing Mechanism for Centrifugal Compress'ors','of'which the following isa specification.

Thepresen t invention relates to centrif- 1 cg-a1 compressors, such as are used for comvpressing air o iotlierrgases, and has for its object'to provide an improved apparatus for pieventing' the pulsations of the column of ,or other gas flowing-[through the mait discharge to atmosp compressor is described .as a machine. for

liaindlingair, but it will be understood that my invention is not limited to this use. Pulsation's m a centrifugal compressor are foundTt'o occur under certain conditions of lightloa'd, and it is known that they may be prevented throttling the intake of the compressor, orby wasting air from the dis- ;c' charge side of the compressor, as by letting to the inlet. 7 v Ilhave found that the point at which pnlsaitibns occur in any machine depends upon gmthe oln'mc of air which the machine is han dling and. the pressure of the discharge. 'Iii jither'words, for every volume there is a critical discharge pressure above which pii 'l'sa tions' arejliable to occur, and vice versa .for'every discharge pressure there is a critic olume below which pulsations are liable t occur. The critical pressures and voluine s n dlfl'erent machines vary cohslder- Specification of Letters Patent.

are or icy-passing it v Patented Oct; 8, 1913-.

Application filed February 2, 1917. Serial No. 146,085.

lune of air per unit of time passing through the machine, and in the following specifica- 65 tion and drawing 1 have specificallydi-sclosed my invention as applied to :such a machine. p I

For a consideration of what I believe. to be novel and my invention, attention is directed to the accompanying specification and the claims appended thereto.

In the accompanying drawings, Figure 1 is a diagrammatic view in side elevation of a turbo-compressor set -provided with a pulsat-ion preventing mechanism embodyingn'ly invention, and Figs. 2 and 3 are sectional views of certain details.

Referring to the drawing, 5 indicates an elastic fluid turbine and 6 a centrifugal com 10 pressor driven thereby, the rotors of both being on the shaft 7. 8 indicates a-valve' mechanism which controls the admission of elastic fluid to the turbine and which may be of any suitable type, an ordinaryand 76 well known form being shown forth-e purposeof illustration. The exhaust ,conduit of-the turbine is shown at 9. The valve mechanism 8 is moved by theflnid actuated motor 10, the stem 11 of which has are-ck 12 engaging a gear wheel 13 on' the cam shaft 14 of the valvemechanism. 15 -indi-; cates the pilot valve of the fluid motor 10 having its stem 16 connected to a floating lever 17. One end of lever 17 is connected by a link 18 to a lever arm 19 pivoted at one end to a fixed support 20 and connected v at the other end to the stem 11 by a suitable connection comprising aslot and pm as m I dicated at 21. The other end of lever 17 isfflfl connected by a rod 22 .to a floating lever 23, one-end of which is connected by a link 24f I 1 to the governor lever 25 of a speed earnor 26 driven from the shaft 74 -The'oth end of floating lever 23 is piv otedon 'th end of a slio rt arm 27 fixed to thebeam'gtl of a constant. vol1ime governing mechanism;

The beam28 is pivoted at 29 on a support. I 30 and is adapted to be tilted by a float 31.,

\ located in the intake conduit 32 of the com-i pressor and connected to the beam by aired The float 31 rides on the air entering the compressor and its action is balanced by a weight 34 which is termed the constant volume governor weight. Journaled on' the beam is a rod 35 having threaded portions .take control in case of excess speed.

may be turned. The weight Z-l-l has a threaded portion which engages the thriaided portion 36 of rod 35 so that by turnin; the hand wheel the weight may be adjusted along the beam 38/ 39 indicates a dash pot for steadying the movements of the beam and it) a balancing weight. M indicates the exhaust conduit of the compressor.

The.arrangement so far dcscrihei'l comprises a well known type of constant volume governing mechanism for a turbine driven compressor. the operation of which will now be. hriefly described.

The constant. volume governor weight 3+ is set on.the beam :28 for the flow of fluid desired. For this purpose a suitable scale or other means (not shown) is provided to guide the attendant. lhe float ill acts on the beam 28 to tilt itr'so as.to cause the fluid motor 10 to open and lose the valve mechanism 8. which in turn admit more or less fluid to the turbine and tlicrclrv causes such regulation in the speed oi the turbine as to obtain suflicient air discharge pressure for the compressor as is required to force the proper quantity or volume oi' air through the discharge conduit ot' the compressor. lt' the sliding weight M is set for a certain volume of air and less air flows past the float 1-51. the float lowers a little. thus tilting the beam 28 in an anti-clockwise direction. This Hits the end of lever 23-which is attached to arm 27. the link "it acting as the fulcrum. The rod 22 is thus lifted and through lever 17 lifts the pilot valve. 15 so that the fluid motor 10 acts to open the valve mechanism 3 to admit more elastic. fluid to the turbine. causing an increase in the speed of the turbine and coinpressoi. Increase of speed of the conmressor raises t he pressure of the discharged air aml also the volume delivered and tlieretore more air passes by the float 3t tending to raise the same and place it in the correct 1.-osition tor the volume of air desired. On the other hand. if the volume tends to increase then the float will raise and tilt the. beam in the opposite. direction. This motion will begin to close ofl the. elastic fluid supplied to the turhine as already explained until the unit will have reached a proper reduced speed for the volume of air desired. The speed gov ernor 26 is normally inactive. the turbine being wholly under the control of the constant volumegovernor and only comes into play to In other words, it soinewhat'ot' the nature of an eniergeney governor.

Referring now to the application of my improved pulsation preventing mechanism to. d. turbo-conipressor" set as just described. 45 indicates a valve arrai'iged in the inlet conduit 32 and having an operating arm 46 connected to valve spindle 47. This is a pulsation preventing valve and is operated 3t) and -57 and a hand wheel 38 by which itmotor 48. the stem 4-? of which is connected" to arm it}. 50 indicates the pilot valve of the motor 4-5. The stem 51 of the pilot valve is connected to a lever 52. one end of which is (.(Hllitt'l'tll by a link 53 to a floating lever fi-l. and the other end by a link 55 to the arm +6. One end of lever 54 is con nected to one end of a rod 56, the other end of which is pivoted to a block 57 which slides in guide-ways 58 on the beam 28. The guides :38 are in vertical alineinent with the pivot point '29 so that the tilting of the beam 28 does not afl'ect the position of the floating lever 54. ()n the beam 28 is a pair of longitudinally extending guides at) in .which slides a plate (50 having a cam slot til therein. Projecting into the cam slot (31 is a short pin (.12 carried by the block 57. (see Fig. 2). The plate (it) is connected by a rod 63 to a nut til which engages the threaded portion 37 of the rod 55. liy this arrangement it will be se n that when the hand wheel 38 is turned to set he constant volume governor weight H the not (it will also be adjusted along the threads 37 to move the plate (it). The other end of floating lever 54 is connected to the stem (.35 of a pressure responsiv device here shown as a cylinder (36 in which moves a piston (37. The cylinder (at below piston 67 connected by conduitlib to the discharge conduit 41 of the compressor. The piston (17 is thus subjected to the pressure. on the discharge side of the coin- (39 is a spring which opposes the movement of the piston (37. Referring particularly to Fig. 3. 70 is a sleeve on the top of the cylinder (36 through which the stem (35 freely passes. The sleeve has a threaded g portion 41 on which screws a nut 12. On the stem (35. spaced a short distance from the sleeve 70. is a shoulder Ti) against which rests a member H to which is fixed a hand wheel 73. One end of the spring 69 is fixed to the nut 7:? and the other endis fixed to the member H. The nut '72 is normally sta tiouarv while the member 7% moves with the stem Ti-3. It will thus be seen thatthe piston (37 moves againstthe tensibfh of the spring (35 The tension of the spring may be adjusted by turning'the hand wheel 75 which serves to turn the member 74, spring 69. and nut 72, thus running the nut. up or do wn the thread 71 as t-lie'case may be.

As already stated the 'iulsation preventing valve 4.5, .it' it is to prevent pulsations. must be set. in aecordai'ice with the volume which 1 til Elli

line of the constant volume governor weight there isa corresponding setting of the aetuating mechanism for the pulsation prevent ing valve 45. When the Weight 3-1- is set by turning the'hand wheel 38 the block. 57 is simultaneously moved in the guides 58 due to the pin (32 engaging the cam slot 61 in plate 60, to set the actuating n'iechanism for the pulsation preventing" valve 15 in accordance. with the volume for which weight 34 is set. Assume, for example, that the hand wheel 38 is turned in a. direction to adjust the weight 34 toward the right. This will act to simultaneously move the nutfi l and plate toward the left. The cam slot 61 will slide along pin 62 and raise the block 57 a certain amount. This will lift the right'hand end of floating lever 5% which will fulcrum on the stem 65, and through link 53 and stem 51 will lift the pilot valve 50 admitting motive fluid above the piston of the motor is causing it to lower slightly, thereby moving or tendingto move the valve l5 toward closed position. When the valve moves toward closed position, the pilot valve is brought back to its normal position through the connection comprising link and lever 52, these parts acting as a usual :t'oi'ni of followup device. This sets the pulsation preventing valve, or, in other \'V()If lS,-ll1(-i operating mechanism for the valvento a position which bears a certain reintion to the volume for which the constant 'xCohnn-e governing mecl'ianisn'i is set. it now the delivery pressure of the rompressm' hecomes of such value that, for the volume being de cum or a about to or then the pressure acting through. the con it W on the pislon iii moves it slightly a mat the. tension oi spring (323.- lhis tllha t in floating lever 5 2, on the end of rod 56 as a pivot, thereby lifting the pilot valve 50 which, in the manner just described, tends to e we to a greater or less extent the pulsation preventing); valve Ila-Will, thusseen that the valve 45 is at any particular instant in accordance with hoththe volume and the delivery pressure. 1

It will he luulerstood, oi" course, that it is ""ble to throttlethe intake only when my, such throttling means, of a slightioss in eliiciency, and earn 61 pod, and the pressure responsive device (il 37, is so adjusted, ti l ,until a con. llllLlOIl of vol ume and pressure is reached at which, pulsations are likely to occur, the alve will be entirely open. in other \v u'ds, it is'only when a'certain relation of miiune to pressure obtainsthat the pulse? lion preventing valve istn; erated.

aom'irdaoce with the pr T have do an. my in averted, pulsations are likely to ocriipresent the hest embodiment thereof; but

I desire to have it understood that the apparatus shown is only illustrative andthat the ii'i'veution can he carried out by other means.

lVha-t I claim as new and desire to secure by Letters Patent of the lh'iited States, is

1. The eoi'ubinathm with a centrifugal compressor ha ving a constant volume governor, of a pulsation preventing valve mechanism, and means for setting it simultaneously with the setting of the constant volume governor.

2. The combination with a centrifugal compressor having a constant volume governor comprising a governor Weight and means for adjusting it, ot a pulsation pre-' l g the effective action of such pressure on the valve mechanism in accordance with the setting of the constant volume governor Weight.

l, The combination with a centrifugal compressor having a constant volume governor comprising a pivoted beam and a vein-ht adjustable thereo of a pulsation preventing valve niechani Ill,-Il1ttf15 responsive to the pressure on the delivery side of the compressor for positioning said valve mechanism, and means including a member slidahle on the beam and having a cam surface for also positioning said valve mechanism, said last named means being positioned in accordance with the volume of fluid entering the compressor.

5. The combination with a centrifugal compressor having a constant volume overnor comprising a pivot-ed heam, a wel ht thereon, and means for adjusting-the weig it,

of a pulsation preventing valve located in the intake of the compressor, mechanism for moving said valve, a movable abutmentre-- sponsiveto the ",JFBSSUL'B on the delivery side of the compressor for actuating said meohanism, and a plate having a cam slot therein for also actuating said mechanism, said plate being operatively connected to said weight adjusting means so as to be moved simultaiwoasl v therewith,

ii. The combination. with a centrifugal est; having eon, ant. volume govnor comprising: pivoted beam, a weight for-also actuating said n'leclianism, said plate being located 011 the beam and operatively connected to said weight adjustingmeans s0 10 as to be moved simultaneously therewith.

In witness whereof, I have hereunto set my hand this 80th day of January, 1917.

RICHARD H. RICE. 

